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Re: [Xen-devel] cpuidle causing Dom0 soft lockups

To: Jan Beulich <JBeulich@xxxxxxxxxx>, Ke Yu <ke.yu@xxxxxxxxx>
Subject: Re: [Xen-devel] cpuidle causing Dom0 soft lockups
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Tue, 23 Feb 2010 10:57:18 +0000
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On 23/02/2010 10:37, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:

>> Right. According to the code, there should be no way to this BUG_ON.
>> If it happens, that reveal either bugs of code or the necessity of
>> adding code to migrate urgent vcpu count. Do you have more
>> information on how this BUG_ON happens?
> 
> Obviously there are vCPU-s that get inserted on a run queue with
> is_urgent set (which according to my reading of Keir's description
> shouldn't happen). In particular, this

Is it possible for a polling VCPU to become runnable without it being
cleared from poll_mask? I suspect maybe that is the problem, and that needs
dealing with, or the proper handling needs to be added to sched_credit.c.

 -- Keir



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